The present invention relates to a camera with an installation structure of a lens for light measurement by which a lens for light measurement is installed in a camera.
A lens for light measurement of a lens-shutter type camera is provided in a camera body in such a manner that its light-receiving portion is disposed adjacent to the photographing lens. This light receiving portion includes a light-receiving element and a lens for focusing an objective image light onto the light-receiving element. Such a conventional lens for light measurement and its vicinity structure are shown in FIGS. 1, 2 and 3.
FIG. 1 is a perspective view showing a conventional lens-shutter type camera. A camera body 51 is provided with a photographing lens 52 at a central portion on its front surface, a finder 53 above the photographing lens 52, and a release button 54 on its top surface. Then, a circular photometry hole 55 is opened adjacent to the photographing lens 52. A lens 61 for light measure is disposed at an innermost end of the photometry hole 55.
An installation structure of this lens 61 for light measurement is explained with reference to FIGS. 2 and 3. The photometry hole 55 is formed in such a manner that a diameter at a cross-sectional plane, which is parallel to a front surface of the camera body 51, becomes small as this cross-sectional plane is located toward an innermost side of the photometry hole 55 (i.e., hole 55 is bevelled). The lens 61 for light measure is coupled into this photometry hole 55 from the inside of the camera body 51. An objective side surface of the lens 61 for light measurement is formed as a convex surface 62, and this convex surface 62 is located just inside of the photometry hole 55.
The lens 61 for light measurement is fixed to the camera body 51 by a lens and a light receiving holder 71. The lens and light receiving holder 71 comprises a diaphragm portion 73 for limiting a quantity of light entering a light receiving element 81. The light-receiving element 81 is disposed behind the lens and light receiving holder 71. The light-receiving element 81 is accommodated in an enclosed cylinder (i.e. a light-shielding cylinder) 77. The enclosed cylinder 77 is fixed on a fixing plate 75, the fixing plate 75 is secured to the camera body 55.
However, in the above-described lens for light measurement there was a problem such that dust or dirt or water droplets tend to remain in the photometry hole 55. When such an obstacle is left in the photometry hole 55, the light quantity reaching the light-receiving element 81 is decreased.
Therefore, brightness of the objective is mistakenly judged to be smaller and, as a result, the photograph becomes overexposed. Or, a photometry distribution will be unexpectedly changed. For example, a central intensified photometry becomes as if it were an averaged photometry and, accordingly, an appropriate exposure amount is not obtained.
Moreover, since it is usual that the photometry hole 55 has a small diameter, removing dust and the like from the inside of the photometry hole 55 is not easy.